Slides in this set

Slide 1

Slide 2

Ice on the LandHow does Ice Shape the Land?Glaciers modify and enlarge features that existed before the Ice Age. The effects are greatest in upland areas where glaciers have been present for the longest time and where the ice was deeper.WeatheringThis means rocks being broken down by weather in glaciated highlands. Freeze-thaw is most important :· Water fills in a crack in a rock· The water freezes and the crack is made wider· The rock breaks into several pieces…read more

Slide 3

ErosionThis means rocks being worn away by moving ice. The ice erodes in 2 ways:· Abrasion­ Rocks and rock particles embedded in the bottom of the glacier wears away the rocks over which the glacier passes. These sharped edged pieces of rock are used as tools. Smaller rocks have a sandpaper effect. While sharp edges of the large rocks make deep grooves called striations.· Plucking­ This is the tearing away of blocks of rock from the bedrock as the glacier moves. These rocks had been frozen in the glacier.Valley glaciers are more effective at erosion that ice:· In the valley, the ice touches both the floor and the sides.· Valley glaciers flow more quickly , because of the steeper gradients and more melt water is present to lubricate the flow.· There is a plentiful supply of rock fragments, so these glaciers are well supplied with tools for abrasion.…read more

Slide 4

Landforms of glacial erosionIce is an increasingly powerful agent of erosion and it can for spectacular landforms in mountainous areas.Corries and TarnsCorries, also known as cwms or cirques, are often the starting point of a glacier. Corries are large. Circular rock hollows on the upper slopes of glaciated valleys characterised by having a steep backwall and a raised lip ate the front. A corrie may contain a lake called a tarn.…read more

Slide 5

1) Snow collects on a mountainside and is compressed into ice in a hollow.2) Freeze-thaw weathering affects the back hollow and makes it steeper.3) Blocks of rock are pulled away from the backwall by plucking4) The glacier uses the loose rocks to scrape out the bottom of the backwall because of the rational slip movements5) This results in a deep hollow, with a steep backwall and a rock lip at the front, where less erosion occurs and some material may be deposited6) After the ice melts a tarn lake may form.…read more

Slide 6

Arêtes e.g. Grib Goch, Snowdonia, North Wales· The sharp, knife-edged ridge at the top of a mountain between two corries.· In any questions about the formation of an arête, write down the 7 stages in the formation of a corries and then add the following stages:· As the backwall of the corries are cut back by weathering and plucking, the ridge between them becomes sharper and narrower· This ridge is kept sharp by freeze-thaw on the mountain peaks…read more